81897494 has 8 divisors (see below), whose sum is σ = 140395728. Its totient is φ = 35098920.

The previous prime is 81897481. The next prime is 81897509. The reversal of 81897494 is 49479818.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2924897 + ... + 2924924.

It is an arithmetic number, because the mean of its divisors is an integer number (17549466).

Almost surely, 2^81897494 is an apocalyptic number.

81897494 is a deficient number, since it is larger than the sum of its proper divisors (58498234).

81897494 is a wasteful number, since it uses less digits than its factorization.

81897494 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5849830.

The product of its digits is 580608, while the sum is 50.

The square root of 81897494 is about 9049.7234211881. The cubic root of 81897494 is about 434.2670424324.

The spelling of 81897494 in words is "eighty-one million, eight hundred ninety-seven thousand, four hundred ninety-four".